JPS6243192B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a display board using a liquid crystal, an electroelastic deformable material, an incandescent material, a heating material, a thermosensitive coloring material, etc., and the optical characteristics of the display board are substantially dependent on the effective value of the applied voltage. The present invention relates to a display device in which display elements are connected with electrodes in a matrix. [Disadvantages of the Prior Art] First, the term "operation margin" used to express the merits of the matrix drive system will be explained. In the matrix driving method, display elements are arranged in n rows and m columns, and a row drive signal of voltage r(t) is applied to the row electrodes, and a column drive signal of voltage C(t) is applied to the column electrodes. The display element at the intersection shows one period T of the drive signal. A voltage with an effective value of is applied. According to the pattern to be displayed, a state in which a high effective voltage is applied to some display elements (hereinafter referred to as the on state) and a state in which a low effective voltage is applied to other display elements (hereinafter referred to as the off state) is set. When the waveforms of the drive signals r and C are given, the minimum voltage applied among the display elements in the on state _{is Vpo} , and the maximum voltage applied among the display elements in the off state _{is Vpff.}
The ratio of α=V _po /V _pff is called the operating margin of the drive method. V _po , V
Although the absolute value of _pff itself changes depending on the power supply voltage, the operating margin is a constant that cannot be determined by the driving method, and is a guideline for determining the quality of the driving method. In a twisted nematic liquid crystal display, the optical characteristics change quite gradually in response to changes in voltage, so good contrast cannot be obtained unless the driving method has an operating margin of about 1.7 to 2. Especially when displaying a clock, etc., the power supply voltage changes over a wide temperature range. For applications that require a beautiful reflective display that can withstand fluctuations, it is better to have as much operating margin as possible. The operating margin in the conventional technology will be described. In the conventional driving method, when driving a matrix of n rows, the row drive signals have a constant signal waveform regardless of the display pattern, and waveforms with symmetry between the row signals are used. Since a drive signal with a drive signal system that can display a combination of patterns was applied to the row and column electrodes,
The operating margin is small, for example, in the 1/2 bias method using a 3-level power supply with two power supplies, α=√(+
3)/(n-1) 4 power supplies In the 1/3 bias method using a 4-level power supply, α = √ (+8), so it is quite difficult to drive a matrix with rows of 4 or more digits. It was difficult. If we consider the conventional drive method in detail,
Among the 2 n-power types of patterns, there are patterns that are easy to drive, that is, easy to increase the operating margin, and patterns that are difficult to drive, that is, bad patterns that become a hindrance in increasing the operating margin, and the actual operating margin is determined. This is the case when a combination of specific patterns occurs between several columns. Since the conventional drive system employs a drive signal having a drive system that can handle all patterns including the worst pattern, the operating margin has been kept small. [Key Points of the Invention] In practical displays of numbers, characters, graphs, animations, etc., the display elements that are turned on and the display elements that are turned off often have some degree of relationship. Taking this into consideration, it is not necessary to be able to deal with all 2 to the nth power of patterns. In the present invention, the display elements are connected and arranged so that the worst-case pattern does not occur, or only a combination of patterns that are easy to drive is generated, and a drive system suitable for the pattern to be displayed is adopted, and a drive system with a large operating margin or Since a drive signal with a small number of power supplies is applied to the row and column electrodes, beautiful displays with good contrast can be easily obtained, especially for displays using reflective twisted nematic liquid crystal displays such as watches and calculators. It is effective when used in equipment. [Vector representation of voltage waveform] For the sake of the following explanation, vector representation of the drive signal waveform will be described. One period of the drive signal waveform is divided into several sections t ₁ , t _{2 ,} . . . t _j , and the drive signal is at the same potential within each section.
Assuming that the time of one cycle is T, the width of the i-th section is t _i , and the potential of the drive signal is e _i , a j-dimensional vector e with e _i √ _i as the i-th element is defined, and the drive signal waveform E and Point e on the j-dimensional orthogonal coordinates is associated with each other.
n square wave voltage signals F ₁ (t), F ₂ (t),...
. . . When F _r (t) is made to correspond to vectors by using the same method of dividing the intervals, it becomes f ₁ , f ₂ . . . f _o . The distance between the coordinate points f _k and f _l is equal to the effective value of the potential difference between the signal waveforms F _k and F _l . In addition, the signal waveforms F ₁ , F ₂ ...... F _o are vectors by dividing the sections in another way.
Suppose that f ₁ ′, f ₂ ′...... are converted into f _o ′. coordinate point
f ₁ , f ₂ . . . f _o and f ₁ ′, f ₂ ′ . . . f _o ′ are congruent. That is, f ₁ , f ₂ , . . . , f _o and f ₁ ′, f _{2 ′} , . Conversion from a vector to a signal waveform is also performed by reversing the above procedure. In this case, too, there is no unambiguous way to divide the sections, so when the vectors f ₁ , f ₂ ......f _o are converted into signal waveforms, F ₁ (t), F ₂ (t) ...... F _o (t) apart from
F ₁ '(t), F ₂ '(t)...... Can be converted into F _o '(t). However, the signal waveforms converted from the vectors f ₁ , f ₂ ......f _o and the vectors f ₁ ′, f ₂ ′...f _o ′ obtained by rotational translation translation inversion transformation
The set of F ₁ , F ₂ . . . F _o forms a set having exactly the same properties from the viewpoint of the effective voltage applied to the display element. If the i-th element can be set to 0 for all vectors during rotational movement or translation, the dimension can be reduced by one order, or it is also possible to increase the dimension by adding a 0 element to all vectors. [Symmetry of row drive signals] The symmetry of row drive signals is defined as follows. Row drive signal r ₁ (t), r ₂ (t)...r _o (t)
, the average value of the row drive signal potential at each instant is
r ₀ (t), i.e. Then, for one period T of the drive signal, 1/T∫ ^T (r _i −r ₀ ) ² dt is equal to a constant value R ² regardless of i, and 1/T∫ ^T (r _i −r _j ) ² When dt is equal to a constant value 2nR ² /(n-1) regardless of i and j when i and j are not equal, the row drive signal is said to have symmetry. In terms of vector expression, this condition is _expressed as r ₁ , _{r 2 . j} , r _k on one side √
This means that it forms an equilateral triangle of 2 ² (-1). [Relationship between on-voltage off-voltage and drive waveform] Let C(t) be a column drive signal for a column that turns on display elements in rows w of n rows and turns off rows (n-w).
Sum of squares of voltage across display elements in off state is the average value of the signal in the off row _pff (), i.e. Using, can be expressed as the sum of squares of the voltage applied to the display element in the on state. is the average value of the ON row signal _po () using It is expressed as [Local optimization of drive waveform] In order to maximize S _po while keeping S _pff constant, C on the extension of the straight lines r _pff and r _po in vector representation.
All you have to do is take . Using a positive coefficient A (

[Overall optimization of drive waveform and worst-case pattern]

Based on these equations, the number k of on-display elements in the worst pattern and the optimal value of A at that time can be determined. The procedure is (a) tentatively determine the value of V _po ² , and (b) from 1 to (n
The value of A corresponding to V _po ² is determined for each w up to -1). (c)w from 1 to (n-1)
Find V _pff ² corresponding to each A for each A, and calculate its maximum value as (V _pff
² ) _Nax . Through these steps, (V _pff ² ) _nax has been found as a function of V _po ² , and w, which determines (V _pff ² ) _nax , is determined so that V _po ² is determined to maximize the operating margin. The number of on-display elements in the worst pattern is k. This can be determined by calculation, but it is easier to predict based on Figure 1. Figure 1 shows V _po ² −
The above equation is shown with V _pff ² on the horizontal axis and V _pff ² on the vertical axis, and w as a parameter, and the group of parabolas 2, 3, 4, 5 passing through the point (0, R ² ) is... It becomes 6. The constant relationship of V _po ² is represented by straight line 1 with a slope of -1, and the value of V _pff ² in step (c) is represented by the intersections of straight line 1 and parabolas 2, 3, 4, 5, and 6, (V _pff
² ) _nax is the upper left intersection 7 among the intersections. When V _po ² is changed (V _pff ² ), the point indicating _nax moves along a curve 8 (indicated by a thick line in the figure) created by connecting the maximum curves. In order for the operating margin α to be large, the smaller V _pff ² /(V _po ² −V _pff ² ), the better. Therefore, when point P is placed on curve 8, a straight line connecting origin 0 and P touches the curve. This represents a limit that cannot be exceeded by the operating margin of the drive signal system capable of displaying any combination of patterns. Expressing this mathematically, if n≧3, there is an inequality It can be seen that there is only one integer k that satisfies , and that the straight line OP is tangent to a parabola with the number of on-display elements w=k. At this time, the constant A and the operating margin α are It is. When n=2, point P is the intersection of the straight line with w=0 and the parabola with w=1, and A=2 and α=3. Practical drive signal systems that can be combined with all patterns, such as the conventional 1/2 bias method and 1/3 bias method, do not necessarily have an ideal value of A due to restrictions on power supply voltage and number of power supplies. Although it is not always possible to generate a column drive signal, the state in which k display elements in n rows are turned on still limits the operating margin. The worst pattern is that when n≧3, there are columns that turn on display elements in k rows out of n rows and turn them off (n-k) at the same time in all combinations, so n=2
So, there are 2 types of columns and 2 columns that turn 1 row on and 1 row off.
The column that turns off the row exists at the same time. [Structure of the present invention] In a conventional display device, when n display elements are connected to one column electrode, each display element independently assumes an on state and an off state;
The drive system was designed to handle ⁿ types of on/off states. As mentioned above, it is theoretically most difficult to display a display in which k display elements in n rows are turned on, and therefore it has been impossible to obtain a high driving margin. The present invention aims to limit the display of such difficult-to-display patterns, optimize the drive waveform under relaxed constraints, and increase the operating margin. Expressing this concretely, let s be an integer smaller than k, and l be an integer larger than k. The display constraints are as follows: (a) The number of display elements that are turned on at the same time is less than or equal to s or greater than or equal to l. In other words, the number of display elements in the on state is from S+1 to l.
Make sure that the number does not exceed -1. (b) The number of display elements that are turned on at the same time is l or more. In other words, the number of display elements in the on state is prevented from becoming less than l-1. Choose one of the following. Corresponding to this, parabolas 1, 2 in Fig. 1...
Among them, the parabolas from s+1 to l-1 are removed, so the curve 8 swells lower than in the conventional method. Since the point P, which is the optimum point of the drive waveform, moves lower, it becomes possible to increase the operating margin α. If the straight line OP touches the sth parabola at point P, the optimal value of A when driving a column that turns s display elements on and n−s display elements off is A. =√(-1)(-), and if the straight line OP touches the l-th parabola at point P, then l display elements are turned on and n-l display elements are turned off. A when driving columns
The optimal value of is A=√(-1)(-), and when point P is the intersection of the sth parabola and the lth parabola, s display elements are turned on and n−s a column that turns off display elements, and l
The optimum value of A when driving a column that turns on display elements and turns n-l display elements off is A=2/n-s-l. The configuration of the present invention is such that under the conditions (a) and (b) above, the drive waveform r _i (t) is applied to the i-th row electrode,

[Explanation based on examples]

Next, a first embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. Figures 2A and 2B show the combined arrangement of display elements when applied to a time display device. Figure 2A shows the connections of the row electrodes 21, 22, 23, and Figure 2B shows the column electrodes 24 to 31. shows the connection. By connecting in this manner, no matter which column electrode is taken out and viewed, a state in which the display elements in one row are turned on and the display elements in the other two rows are turned off does not occur. This eliminates the worst case pattern, and also eliminates all situations where the number of on-displays w is k=1.
Draw a diagram similar to Figure 1 for the case of n = 3.
If we exclude the curve of =k=1, then the next bad pattern that restricts the operating margin is w=s=
It can be seen that this is the intersection of 0 and w=l=2. It can be seen that the ideal value of A at this time is 2, and the limit of the operating margin is √7. The column electrode 25 has a display element 32 representing a ten-digit number at the intersection with the row electrode 21, and a display element 33 representing an l segment at the intersection with the row electrode 23, so that one side is on and the other is off. 25 does not have a display element at the intersection with the row electrode 22, so the bad pattern referred to here, where one row is on and the second row is off, does not occur. For example, when one of the display elements 32 and 33 is on, a drive signal that turns on the row electrode 22 is also supplied, and when the display elements 32 and 33 are turned off at the same time, the row electrode 22 is also turned off. It is sufficient to supply a drive signal that becomes Furthermore, although the column electrode 29 has four display elements, the display element 34 indicating the α segment and the display element 35 indicating the d segment may be considered to be the same. This is the next bad pattern. Number of on-display elements w = 2
Since rows with display elements that are turned off in a pattern may occur in three rows at the same time, making the row drive signals asymmetrical does not help. If the row drive signals are symmetrical, the row drive signals r ₁ , r ₂ , and r ₃ are located at the vertices of an equilateral triangle on the circumference with radius R in vector representation. Column drive signal C ₀ for the column that turns off all rows
is preferably located near the center of the equilateral triangle. The column drive signal C ₁₂ for the column that turns on the first and second rows and turns off the third row has a distance R from the row drive signal r ₃ , and r ₁ , r ₂
It is best to choose the point farthest from. The column drive signal C ₁₂₃ for the column that turns on three rows at the same time must be separated from r ₁ , r ₂ , and r ₃ by at least a distance of C ₁₂ − r ₁ , so the ideal signal as shown in Figure 3 A is ideal. If a suitable position is given, the operating margin can be increased to the limit of √7. That is, r ₁ , r ₂ , and r ₃ are located on the circumference of a circle with radius R centered on point C ₀ and form an equilateral triangle. Three points C ₁₂ , C ₁₃ , C ₂₃ also have radii centered on point C ₀
It is on the circumference of 2R and forms an equilateral triangle, with three points
C ₁₃ r ₂ C ₀ , C ₂₃ r ₁ C ₀ , and C ₁₂ r ₃ C ₀ are arranged on a straight line. Additionally, this can be expressed using the following rules as explained later. That is, r ₁ , r ₂ , r ₃ are the vertices of an equilateral triangle centered on C ₀ , and the column drive signal Cab that turns on rows _a and _b is the average value _ab and r ₁ , _r2 ,
It is located at a position where the straight line connecting the average value C ₀ of r ₃ is extended twice the distance. Although C ₁₂₃ does not appear on the diagram, it is located at a distance of √6R from C ₀ perpendicular to the plane of the paper. As shown in FIG. 3B, if the figure in FIG. 3A is placed obliquely in a three-dimensional space, each point will exactly match the grid point, and it can be seen that it can be driven using four electric and five-value levels. The vector in FIG. 3B is converted into a drive signal waveform by associating the x coordinate with section _t1 , the y coordinate with section _t2 , and the z coordinate with section _t3, and is shown in FIG. 4A. Furthermore, if the figure in FIG. 3A is slightly modified and applied to the structure points as shown in FIG. 3C, it can be seen that it can be converted into a signal of two power supply and three-level levels. This waveform diagram is shown in FIG. 4B. This operating margin is √5. This is due to the fact that C ₀ deviates from the average value r ₀ of r ₁ , r ₂ , r ₃ , and that C ₁₂ is not on the extension of the straight line connecting r ₀ to the average value ₁₂ of r ₁ and r ₂ . This results in a decrease in the operating margin of the device. The waveform should show only the essential half cycle, and an inverted waveform should be added to the remaining half cycles so that there is no DC component. A second embodiment will be described with reference to FIGS. 5 and 6. FIG. 5 shows a combined arrangement of display elements when applied to a numeric display device, where FIG. 5A shows connections of row electrodes and FIG. 5B shows connections of column electrodes.
Since the decimal point is not displayed in the display of numbers 0 to 9 and in the zero suppressed state, no matter which column is selected, a state in which the display of one row is on and the display of the other three rows is off does not occur. First for the case w=4
If you draw a diagram similar to the one shown in the figure and exclude the curve with w=1, the bad pattern that restricts the operating margin is w=2.
It can be seen that A=1 is ideal, and in this case, the operating margin is √113≈1.932. Expressing the relationship between the drive signals at this time as a vector, the row drive signals r ₁ , r ₂ , r ₃ , r ₄ form a regular tetrahedron on a spherical surface of radius R centered on the column drive signal C ₀ that turns off all row drive signals. occupies the top position. The column drive signal C ₁₂ that turns on the first and second rows is at a distance R from r ₂ and r ₃ and is farthest from r ₁ and r ₃ . For w=3 and w=4, the constraints are loose and there is a considerable degree of freedom, so the size of V _po can be determined later. The ideal column signal with C ₀ and w = 2 is expressed as a vector as shown in Figure 6.
It is determined on a dimensional grid point. From this, a waveform of 4 power supplies and 5 levels can be obtained immediately. However, the number of power supplies can be reduced by applying appropriate coordinate transformation. FIG. 7 shows an example of a drive waveform of two power supplies and three levels. Furthermore, in general cases, the drive signal waveform can be obtained by the following procedure. Number of on-display elements w=1, w= for animation display etc.
2. Suppose that a combination of display elements is arranged so that a column of w=3......w=l-1 does not appear.
With V _po ² - V _pff ² as the horizontal axis and V _pff ² as the vertical axis,
1, 2, 3...For w excluding l-1, equation (2) and
Write the relationship in equation (3) on a graph and create a curve that connects the topmost curve. When a connection is drawn from the origin to that curve, the number of ON elements of the bad pattern can be found based on which curve the point of contact is on, and the column drive signal that drives the column of the bad pattern can be determined from the coordinates of the point of contact. A drive signal system that not only removes the worst patterns but also limits the number of display elements that are turned off greatly improves the operating margin, which has a great effect on graph displays, symbol displays, animation displays, etc.
Sufficient contrast can be obtained even on matrix display devices with more than 10 lines. A third embodiment will be described in which an integer greater than k and less than n is defined as l, and there is no column displaying a pattern in which the number of display elements turned on is from 1 to (l-1) in one column. That is, since w is greater than 0 and l, a bad pattern is determined approximately by the intersection of w=s=0 and w=l. A
The ideal value of can be easily calculated and is 2/(n-l). The limit of the operating margin is α=√1+4{(-1)(-). The drive signal is as follows. Column drive signal for columns that turns off all rows in vector representation Column drive for columns that turns on l rows and turns off (n-l) rows using symmetrical row drive signals centered on C ₀ The signal C _l is on a straight line connecting the average r ₀ of all row drive signals and the average value r _pff of the row drive signals of the row of display elements that are turned off, and C _l , r _pff , r ₀ are C _l Ideally, the distance of r ₀ should be twice the distance of r ₀ and r _pff , but a slight deviation will hardly change the operating margin. There are several ways to determine column drive signals other than C _l . (b) Adopt the A value that makes everything other than V _po the same as C _l . In this case, V _pff is smaller than V _pff of C _l . (B)
The value of A that makes the value of V _pff the same as C _l is adopted.
In this case, V _po becomes larger than V _po of C _l , which is undesirable because it causes uneven shading in liquid crystal displays. (c)
The same value of A as C _l is adopted, and when V _po and V _pff are insufficient, a section is provided where the row drive signals are at the same potential, and a potential difference is given to the column drive signal in that section, so that V _po ² - V _pff
Increase V _po ² and V _pff ² while keeping ² constant. In terms of vector expression, this means that column drive signals other than C _l are provided in a dimension different from the space in which the row drive signals and C _l are included. You can also decide between (a), (b), and (c). In the first example, n=3, l=2,
The second example corresponds to the case where n=4 and l=2. A fourth embodiment will be described in which there is no pattern for turning off all rows from the above pattern. In the case of n-l≦2, the limit of the operating margin increases further. Even if n-l=3 and n>9, the difference is theoretically different from the above case, but the difference is almost 0. A bad pattern turns on l display elements (n
-l) becomes a pattern that turns off the ideal A
The value of is √(-1) {(-)} The limit of operating margin is becomes. When n-l=1, A=1 and the operating margin becomes infinite. FIG. 8 shows how the operating margin is improved in the display device of the present invention. The vertical axis is the theoretical limit value of the operating margin, and the horizontal axis is the number of matrix rows n.
81, 82, and 83 are drive signal systems that can display any combination of patterns including the worst pattern; 81 is based on the 1/2 bias method, 82 is based on the 1/3 bias method, and 83 is based on the drive waveform. This is the theoretical limit without any constraints. 83 to 87 are cases in the first to fourth embodiments of the present invention, and 84,
For 85 and 87, the number of on-display elements is from 1 to (l-1)
With a drive signal system that does not display patterns up to 84
is l=n-3, 85 is l=n-2, 87 is l=n
-1 case. Further, 86 is a drive signal system that does not display a pattern in which the number of on-display elements is 1 to (l-1), and is the case where l=n-2. Up to now, the embodiments of the present invention have been described on the assumption that the drive signals are symmetrical, but from now on, the case where a drive signal without symmetry is used will be explained. This is a case where a bad pattern appears only in a certain line. In the case of a matrix with two rows of display elements, the row drive signals are inherently symmetrical, so the asymmetry becomes a problem with the column drive signals and how they are actually assigned to potential levels. It is. In the case of a matrix having three or more rows of display elements, the row drive signals can be made asymmetrical and, accordingly, the column drive signals can also be made asymmetrical to improve the operating margin. A fifth embodiment of the present invention will be described using FIG. 9. The worst pattern when using display elements with 2 rows and m columns is that both the 1st row and 2nd row are off, and the 1st row is on and the 2nd row is off.
This is a case where columns displaying three types of patterns: row off, second row on, first row off, occur simultaneously. Let's now assume that it is possible to prevent the third pattern from occurring by combining display elements. Among the column drive signals,
A case where both the first and second rows are turned off is _C0 , a case where only the first line is turned on _{is C1} , and a case where both the first and second lines are turned on is _C12 . Ideally, the row drive signals r ₁ , r ₂ and the column drive signals C ₀ , C ₁ , C ₁₂ are arranged in vector representation as shown in FIG. 9A. _r1 ,
C ₀ , r ₂ , and C ₁ are arranged in this order on a straight line at equal intervals,
The distance r ₁ , C ₁ is equal to the distance r ₁ , C ₁₂ and the distance r ₂ , C ₁₂ . If this is assigned to the grid points as shown in FIG. 9B, the operation margin α=3 with three power supplies and four-value levels, which requires one less power supply than the drive signal system that can display all patterns. Further, when allocating in this way, the potential level of the column drive signal may be two levels, 0 and 2R. If it is assigned to the lattice points as shown in FIG. 9C, it can be driven with two power supplies and three levels, and the operating margin will be √6. This is considerably larger than the drive signal system capable of displaying all patterns with the same number of power supplies, which is √5. This is because the conventional one has angles r ₁ , C ₀ , r ₂ and angles
This is due to the fact that the distances C ₁ , r ₁ could not be made large because one _of r ₁ , r 2 , and C ₁ is at right angles and the other is 135°. In the present invention, both (b) and 180 degrees (c) can be set as large as 120 degrees, thereby providing a large operating margin. In FIG. 9C, the coordinates of C ₁₂ are not within this dimension, and the point projected into this dimension is indicated by 91, but this may be anywhere as long as it is approximately equidistant from r ₁ and r ₂ . Since it is extremely easy to create a drive signal waveform from (b) and (c), a description of the drive signal waveform will be omitted. We have explained the case where the row that is turned on is r ₁ , but if the rows that are turned on are r ₁ and r ₂ alternately, the row drive signal can be exchanged each time.
This operation is possible with slight modification of the decoder. Alternatively, the entire level of the drive signal may be shifted. FIGS. 10 and 1 regarding the sixth embodiment of the present invention.
This will be explained using Figure 1. The worst pattern when using display elements of 3 rows and m columns is when a pattern in which 1 row is on and 2 rows are off appears in such a way that all 3 rows are turned on at the same time. Even if this pattern exists, if the pattern that turns on is fixed, the operating margin can be improved by using asymmetric row drive signals. In this embodiment, a case will be described in which a bad pattern in which one row is on and two rows are off does not occur such that the third row is turned on. Row drive signals r ₁ , r ₂ ,
The relationship between r ₃ and column drive signals C ₀ , C ₁ , C ₂ , C ₁₂ , C ₁₃ , and C ₁₂₃ is preferably arranged as shown in FIG. In other words, the column drive signal is located on the circumference of radius R centered on C ₀ , but it is not symmetrical, and the distance between rows that are turned on is r ₁ and r ₂ , and the distance between rows that are turned on and rows that are not turned on is r ₂ , r ₃ and distances r ₁ , r ₃ . In this case, the distances r ₁ and r ₂ are multiplied by the distances r ₁ and r ₃ √2. This means that when the distance C ₂ r ₁ , C ₂ r ₃ , C ₁ r ₂ , C ₁ r ₃ , C ₁₂ r ₃ is less than R, the distance C ₁ r ₁ , C ₂ r ₂ , C ₁₂ r ₁ , C ₁₂ r The minimum value of ₂ is now the maximum. Each coordinate point corresponds exactly to a square grid point with equal side lengths. C ₁₂₃ is located at a distance of 2R from C ₀ perpendicular to the plane of the paper. FIG. 11 shows a waveform diagram of the drive signal obtained based on FIG. 10. The subscript of C indicates the number of rows to be turned on, and 0 indicates that no rows are to be turned on. FIGS. 12 and 1 regarding the seventh embodiment of the present invention.
This will be explained using Figure 3. In this embodiment, bad patterns do not appear in the second and third rows. That is, a case will be described in which there is no other line than the first line that is turned on due to a bad pattern. The row drive signals r ₁ , r ₂ , and r ₃ are located on a circle with a radius R centered on the column drive signal C ₀ , but they are not symmetrical, and the distance between the rows that turn on in a bad pattern and the rows that do not turn on. r ₁ , r ₂ and r ₁ , r ₃ should be larger than the distance r ₂ , r ₃ between the rows that do not turn on, and the distance C ₁ r ₂ , C ₁ r ₃ , C ₁₂ r ₃ , C ₁₃ r ₃ is less than or equal to R, and the distances C ₁ r ₁ , C ₁₂ r ₁ , C ₁₂ r ₂ , C ₁₃ r ₁ , and C ₁₃ r ₃ are selected to maximize the minimum value, so the distances r ₁ r ₂ , r ₁ r ₃ is (1+√2) times the distance r ₂ r ₃ . C ₁₂₃ is located at a distance of √2+2〓2 from C ₀ perpendicular to the plane of the paper. Figure 13 depicts the drive waveform based on Figure 12. When converting the z-axis direction to the third section, t ₃
is increased to prevent the power supply voltage from becoming too large. The limit of the operating margin at this time is √4+2〓2. The figure in Figure 12 has 4 points r ₃
C ₀ r ₂ C ₁ is a square with one side R, and each C ₁₂ C ₁₃ r ₁ is on the diagonal of the square, and the distance from the vertex of the square is R. However, the potential levels in Figure 13 are quite complex, and when expressed in V ₁ as a unit, V ₂ is (1+√2)V ₁ , V ₃ is √5+4〓2V ₁ , and V ₄ is √4.
+4=2V ₁ −V ₂ . An eighth embodiment of the present invention will be described using FIG. 14. In this embodiment, display elements of 4 rows and m columns are used, and a bad pattern in which 1 row is on and 3 rows are off does not appear in the first row or higher. The row drive signals r ₁ , r ₂ , r ₃ , and r ₄ are on a spherical surface with a radius R centered on the column drive signal C ₀ , but they are not symmetrical, and some rows are turned on in a bad pattern and some rows are not turned on. distance
r ₁ r ₂ , r ₁ r ₃ , r ₁ r ₄ are the distances between the lines that do not turn on
r ₂ r ₃ , r ₃ r ₄ , r ₄ r ₂ and the distance
C ₁ r ₂ , C ₁ r ₃ , C ₁ r ₄ , C ₃₄ r ₂ , C ₃₄ r ₁ , C ₂₃ r ₁ , C ₂₃ r ₄ ,
C ₂₄ r ₁ , C ₂₄ r ₃ below R and distance C ₁ r ₂ , C ₁ r ₃ , C ₁ r ₄ ,
Since the minimum value of C ₂₃ r ₂ , C ₂₃ r ₃ , C ₂₄ r ₂ , C ₂₄ r ₄ , C ₃₄ r ₃ , and C ₃₄ r ₄ was chosen to be the maximum, the distance r ₁ r ₂ is the distance
It becomes √76 times r ₂ r ₃ . r ₂ r ₃ r ₄ is 2√30 on one side
C ₀ is located 3R/7 from the center of the R/7 equilateral triangle. This operating margin is 13/7. The ninth embodiment of the present invention is shown in Fig. 15, Fig. 16, and Fig. 17.
This will be explained using FIG. Figure 15 A, B,
Figures 16A and 16B show the combined arrangement of display elements when applied to a numeric display device.
FIG. 16A shows the connection of the row electrodes, and FIGS. 15 and 16B show the connections of the column electrodes 155 and 156. 1
51 is the first row electrode 152 is the second row electrode 153
The third row electrode 154 is the fourth row electrode. By combining A and B in Figure 15 or A and B in Figure 16, the numbers 0 to 9 are displayed and the decimal point is not displayed in the zero press state, so the row electrodes 155 and 156 are No matter which column you look at, the display of one row is on and the display of the other three rows is off, and the bad pattern is that the display elements of the second row are on and the display elements of the second row are off. However, it does not occur evenly in all rows, but in the first
There are no bad patterns other than turning on row and second row, first row and third row, and second row and third row. Therefore, by making the row signals asymmetric, the operating margin can be further increased than in the second embodiment. FIG. 17 is a diagram showing an ideal positional relationship between row drive signals r ₁ , r ₂ , r ₃ , r ₄ and column drive signals C ₀ , C ₁₂ , C ₁₃ , and C ₂₃ . The row drive signals r ₁ , r ₂ , r ₃ , r ₄ are
It is placed on a spherical surface with radius R centered on C ₀ , and r ₁ , r ₂ , and r ₃ , which are equally involved in turning on bad patterns, are placed in an equilateral triangle, and the row r ₄ that does not turn on is placed on a regular triangle. vertically above the center of the triangle, the distance
Place it so that r ₁ and r ₄ are smaller than one side of the equilateral triangle. Distance ₁₂ r ₃ , C ₁₂ r ₄ , C ₁₃ r ₂ , C ₁₃ r ₄ , C ₂₃ r ₁ , C ₂₃ r ₄
is less than or equal to R and the distances C ₁₂ r ₁ , C ₁₂ r ₂ , C ₁₃ r ₁ , C ₁₃ r ₃ ,
If we choose to maximize the minimum value of C ₂₃ r ₂ and C ₂₃ r ₃ , the quadrilaterals C ₀ r ₃ C ₁₂ r ₄ , C ₀ r ₁ C ₂₃ r ₄ , and C ₀ r ₂ C ₁₃ r ₄ are is also a square with side R, and the distance r ₁ r ₂ is r ₄ r ₁ √
32 times, and the operating margin is 2. FIG. 18 shows an example of the waveform of the drive signal. 1st
The x, y, and z coordinates in Figure 7 are used as they are in the sections t ₁ , t ₂ , t ₃
t ₁ , so that the voltage levels are integer ratios.
The ratio of t ₂ and t ₃ was set to 3:1:4, and t ₄ was set to t ₃ /4. In the present invention, display elements are connected and arranged so that the worst-case pattern that would reduce the drive margin does not occur, or only a combination of patterns that are easier to drive is generated, and at least the worst-case pattern that reduces the drive margin is arranged. Since the drive signal of the drive system that does not display specific bad patterns including patterns is applied to the row and column electrodes, display with good contrast, display with good temperature characteristics and viewing angle characteristics, increase in the number of drive rows, and power supply It has become possible to obtain a large operating margin amid mutually contradictory demands such as reducing the number of potentials and simplifying the drive waveform, increasing the degree of design freedom to satisfy each demand, and making it possible to create superior electro-optic display devices. It becomes possible to provide

[Brief explanation of the drawing]

FIG. 1 is an explanatory graph showing constraints on operating margins, FIG. 2 A and B are display element arrangement diagrams of the first embodiment of the present invention, and FIG. 4A and 4B are drive signal waveform diagrams of the first embodiment of the present invention, FIGS. 5A and 5B are display element arrangement diagrams of the second embodiment of the present invention, and FIG. A vector diagram of a drive signal according to a second embodiment of the present invention,
FIG. 7 is a drive signal waveform diagram of the second embodiment of the present invention,
FIG. 8 is a graph showing the limit value of the operating margin including the embodiment of the present invention, FIG. 9 is a vector diagram of the drive signal of the fifth embodiment of the present invention, and FIG. 10 is a graph of the sixth embodiment of the present invention. FIG. 11 is a vector diagram of the drive signal, FIG. 11 is a drive signal waveform diagram of the sixth embodiment of the present invention, FIG. 12 is a vector diagram of the drive signal of the seventh embodiment of the present invention, and FIG. 13 is a vector diagram of the drive signal of the seventh embodiment of the present invention. Drive signal waveform diagram of the example,
FIG. 14 is a vector diagram of drive signals in the eighth embodiment of the present invention, FIGS. 15A and 16B, FIGS. Vector diagram of the drive signal of the ninth embodiment of the invention, 1st
FIG. 8 is a drive signal waveform diagram of a ninth embodiment of the present invention. r ₁ , r ₂ , r ₃ , r ₄ ... row drive signal, C ... column drive signal, the subscript indicates the number of the row to be turned on,
C ₀ ...Column drive signal that turns off all rows, 21-23, 51-54, 151-154...
...Row drive electrode, 24-31, 55, 56, 15
5,156... Column drive electrode, 81-87... Curve showing the relationship between operating margin and number of rows, 84-87...
...Drive signal.

Claims (1)

[Claims] 1. Display elements having optical characteristics that depend on the effective values of the voltages applied to the row and column electrodes are arranged in a matrix of n rows and m columns, and each row electrode has r ₁
(t), r ₂ (t), ......r _o (t) In an electro-optical display device that provides row drive signals of voltages, the inequality expressed by the number of rows n Let k be an integer that satisfies the equations 0≦s<k and k<l<n, and let s and l be integers that satisfy the inequalities 0≦s<k and k<l<n, respectively. No matter which one of the column electrodes is taken, it is one column. The display pattern is limited by setting a common s and l so that the number of display elements that are turned on among the display elements connected to the electrodes is either an integer less than or equal to s or more than or equal to l. , when turning on s display elements and turning on l display elements, the column electrodes are (However, r ₀ (t) is the average value of the instantaneous values of all row voltages. An electro-optical display device characterized in that it provides a column drive signal of a voltage that is the sum of row voltages applied to rows to be turned on. 2. In claim 1, a section in which the row drive signals are at the same potential is provided, and less than s display elements are turned on, and more than l display elements are turned on. The electro-optical display device is characterized in that a voltage different from a row drive signal is applied to the column electrodes of at least a portion of the section. 3 Display elements having optical characteristics that depend on the effective values of the voltages applied to the row and column electrodes are arranged in a matrix of n rows and m columns, and each row electrode has r ₁
(t), r ₂ (t), ......r _o (t) In an electro-optical display device that provides row drive signals of voltages, the inequality expressed by the number of rows n is Let k be an integer that satisfies the equations 0<s<k and k<l<n, and let s and l be integers that satisfy the inequalities 0<s<k and k<l<n, respectively. No matter which one of the column electrodes is taken, one column The display pattern is limited by setting a common s and l such that the number of display elements that are turned on among the display elements connected to the electrodes is either an integer less than or equal to s or more than or equal to l. , when turning on s display elements, the column electrodes are (However, r ₀ (t) is the average value of the instantaneous values of all row voltages. An electro-optical display device characterized in that it provides a column drive signal of a voltage that is the sum of row voltages applied to rows to be turned on. 4 In claim 3, there is provided a section where the row drive signals have the same potential, and when less than s display elements are turned on, and when l or more display elements are turned on. An electro-optical display device, wherein a voltage different from a row drive signal is applied to a column electrode of at least a portion of the section. 5 Display elements having optical characteristics that depend on the effective values of the voltages applied to the row and column electrodes are arranged in a matrix of n rows and m columns, and each row electrode has r ₁
(t), r ₂ (t), ......r _o (t) In an electro-optical display device that provides row drive signals of voltages, the inequality expressed by the number of rows n is When k is an integer that satisfies the inequality k<l<n, and l is an integer that satisfies the inequality k<l<n, no matter which one of the column electrodes is taken, the number of display elements connected to one column electrode is A common l such that the number of display elements that are in the on state is l or more
is set to limit the display pattern, and when l display elements are turned on, the column electrodes are (However, r ₀ (t) is the average value of the instantaneous values of all row voltages. An electro-optical display device characterized in that it provides a column drive signal of a voltage that is the sum of row voltages applied to rows to be turned on. 6 In claim 5, a section in which the row drive signals are at the same potential is provided to turn on s or less display elements and turn on more than l display elements. In some cases, an electro-optic display device, wherein a voltage different from a row drive signal is applied to a column electrode of at least a part of the section.